Automatic gun



T. H. EICKHOFF.

AUTOMATIC GUN.

APPLICATION man SEPT. a. 1920.

Patented Nov. 15, 1921.

6 SHEETS-SHtEI l.

Z /04 f7 KM fZy/m T. H. EICKHUFF.

AUTOMATIC GUN.

APPLICATION FILED SEPT. 8I 1920.

Patented Nov. 15, 1921 T. H. EICKHOFF.Y

AUTOMATIC GUN.

APPLICATION FILED SEPT. 5,1920. A 1,395,949.. Patented Nov. 15, 1921.

6 SHEETS-SHEEI 3.

T. H. EICKHOFF. AUTOMATIC GUN.

APPLICATION FILED SEPT. B, 1920. 1,396,949., Patented Nov. 15, 1921.

6 SHEETS-SHEI 4.

T. H. EICKHOFF.

AUTOMATIC GUN.

APPLICATION FILED SEPT. |920.

1,396,949., Patented NOV. 15, 1921.

6 SHEETS-SHEEI 5.

T. H. EICKHOFF.A

AUTOMATIC GUN.

APPLICATION FILED SEPI. 1920.

Patented Nov. 15, 1921.

6 SHEETS-SHtEl 6.

TT FFE.

THEODORE H. EICKHOFF, OF CLEVELAND, OHIO, ASSIGNOR TO AUTO-rORDNANCE COR- PORATION, F NEW/YORK, N. Y1, A CORPORATION OF NEW YORK.

AUTOMATIC GUN.

Specification of Letters Patent.

Patented Nov. 15,1921.

' Application led September 8, 1920. Serial No. 408,912.

i T o all w hom t may concern America, and resident of Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and useful Improvements in Automatic Guns, of which the following is a specification.

This invention relates to an improvement in guns, particularly to firearms of the automatic or semi-automatic types, and more particularly to improvements in lock mechanism and associated firing and recoil mechanism for such arms.

The gun comprises a lock of the type adapted to reciprocate longitudinally as the breech is opened and closed and to be rotated into and out of locking engagement with lock means upon the receiver. The lock shown in the present embodiment operates upon what is Iknown as the Blish angle defined in the patent to Blish, 1,131,319, March 9, 1915.

It is an object of the present invention to provide anew and improved gun ofthe character describedand to provide in connection with such a gun an improved locking means, recoil and recoil housing means, improved firing means andadjustable bolt stop mechanism and to provide improved means whereby the gun may be adjusted for either automatic or semi-automatic fire. It is also an object to rovide new and improved means for closlng the receiver openings and for locking the piece. Other and further objects will appear as the description proceeds.

A specific embodiment is shown in the drawings in which- Figure 1 is a plan view of the portions of the barrel and stock being broken away;

Fig. 2 is a vertical longitudinal section of that portion of the un shown in Fig. 1;

Fig. 3 is an enlargef longitudinal section showing the firing mechanism in the fired position;

, Fig. 4 is a longitudinal section showing the bolt stop in a raised position;

Fig. 5 is a lon 'tudinal section showing the bolt in the fully retracted position;

Fig. 6 is a top view of the gun;

Fig. 7 is a side view of the gun;

Fig. 8 is a, cross4 section through the gun at the cut out mechanism;

Fig. 9 is a fragmentary side view of Fig. 8; i

Fig. 10 is a. fragmentary section showing the cut out;

Fig. 11 is a fragmentary section showing the disconnecter in the inoperative osition;

Fig 12 is a side view of the Felt stop member;

Fig. 13 is a fragmentary section on line 13--13 of Fig. 3;

Fig.- 14 is a fragmentary sectionon line 14-14 of Fig. 3;

Fig. 15 is a fragmentary section on line 15-15 of Ffig. 3;

Fig. 16 lis a longitudinal section of th bolt sleeve;

Fig. 17 is a side view of the pusher;

Fig. 18 is a sectional view of Fig. 17;

Fig. 19 is a sectional view of the locking sleeve; and

Fig. 2O is a development of the locking sleeve.

The gun comprises a receiver 20, a barrel 21, stock 22, The bolt 25 is slidably mounted in the receiver 20, and rotatably mounted on the bolt is the locking sleeve 26. The actuating handle 27 is rigidly connected to the sleeve 26 and extends outwardly through the slot 28 in the receiver 20. Screwed into the'rear end of the bolt is the bolt sleeve 29, best shown in F ig. ,16, which sleeve is kept from rotation by the disconnecting lug 30 which extends downward from the Sleeve and is adapted to move longitudinally in the slot 31 in the lower side of the receiver. Fitting inside the bolt and bolt sleeve is the firing pin 32, having seated upon its forward portion the thrust washer 33 which is countersunk to engage the enlargement 34 of the firing pin. The iringspring 35 surrounds the firing pin, the lfdrward, end bearing against the washer 33 and its rear end against the bolt sleeve 29. The cam pusher member 36 partially surrounds the bolt sleeve 29 and engages the rear end of the locking sleeve 26 and it has the inwardly eirtending lug 37 which ooacts with the longitudinal slot 38 in the bolt sleeve. This lug ard l23, and magazine 24.

37 serves to restrain the cam pusher 36 from rotation and also to engage the cooking extension 39 on the u per side of the rear end of the firing pin. Ks best shown in Figs. 17 and 18 the lower side of the pusher is slotted to permit passage of the disconnecting lu 30 of the bolt sleeve. As shown in Figs. 1 to 20, the engaging surfaces between the pusher and locking sleeve comprise opposed cam lugs 26 .and 36. The safety shutter 40 is fitted into the receiver 20 and is held in place by the screw cap 41. The safety shutter has forwardly extending portions adapted in one position to cover the slot 28 in the receiver and to cover the lower slot in which the disconnecter lug 30 operates, the forward end of the latter portion abutting against the rear of the lug The buffer member 47 slips over the washer 46 and extension 42 and the resilient buffer material 48 is inclosed within the buffer. The recoil spring 49 is contained within the safety shutter and has its forward end bearing against the cam pusher 36 and its rearward end bearing against the circumferential flange 50 on the buffer member 47. The sear 51 is pivotedly connected at 52 to the bolt Asleeve 29.v The forward end of the sear is provided with the rearwardly faced notch 53, adapted to coact with a similar notch 54 in the lower side of the firing pin and the lower end of the sear is provided with a pin 55 which extends rearwardly through an opening in the disconnecting lug 30. This pin 55 is surrounded by the spring 56, the forward end of which bears against the rear face of the sear and the rear end of which bears against the disconnecting lug. The forward face of the lower sear arm is provided with the contact member 57 adapted to contact with the tripper 58 which latter is pivoted in the receiver on the pin 59. The tripper 58 is provided with the rearwardly facing concave surface 60 adapted to coact with the contact member 57 of the scar and the tripper is normally held in position in which it is shown in A Fig.. 5 by the spring 61. The lower side of the tripper member 58 is provided with the engaging notch 62 which coacts with the notch 63 uponA the forward end of the trigger bar 63. The trigger bar 63 passes through the bearing 64 in the guard 23 and its rearward end is engaged with the upper end 65 of the trigger 66. The trigger sprlng 67 surrounds the trigger bar 63 rearwardly of the bearing 64,' the rear end of the spring bearing againstthe washer 68. The forward end of the trigger bar 63 is normally pressed upward by the spring 69 seated in the recess 7 0 in the guard. The trigger bar 63 carries the adjustable disconnecter 71 normally held in the position shown in Fig. 5 by the spring 72. The lower side of the receiver is provided with thelopening 73 to permit passage of the 8l has its forward end normally urged upward bythe spring 83, the lower end .of which bears against the guard 23 and the upper end of which fits in the socket 84 in the bolt stop member. This -member is shown in side view in Fig. 12l and consists of two side plates cross connected by the finger piece 82, and at 85 by the portion bearing against the spring 83 and its forward portion is cross connected by the bolt stop proper 86 having the notch 87 therein. The ejector 81 extends upward from the center of the bolt stop and moves in the slot 25 in the under side of the bolt. The bolt stop release 88 is pivoted in the bolt stop on the pin 89 the forward lportion carrying the spring 90, the upper arm of which bears against the under side of the bolt stop 86. The upper portion 91 of the bolt stop release normally engages the downward extending portion 92 of the receiver which maintains the release in the position shown in Fig. 5. YThe magazine 24 is provided with a follower 93 having the rearwardly extending lug 94 adapted when the magazine is empty to coact with the forward portion 95 of the bolt stop release to rotate the bolt stop release rearwardly about its pivot to disengage the portion 91 yfrom the receiver portion 92. The magazine is provided with the rearwardly extending lug 96 which engages over the spring catch 97 to retain the magazine in the gun. The catch 97 at its upper end is normally pressed forward by the spring 98 and is provided with'the finger operating piece 99 extending downward through the guard. The cut out 100 is carried on the pin 101 having the finger piece.

the locking sleeve 26. The bolt is provided l with the customary extractor 106. The rear sight 107 is mounted upon the upper part of the receiver adjacent its rear end. The barrel adjacent the magazine 24 is provided with the hand guard 108 which is interiorly cut away at 109 and which is held in place by the band 110. The receiver cap 41 is threaded on the rear endof the receiver 20 andis l held against rotation by the upper endfof the bolt 111. The bolt 111 as shown in Fig. 2, is provided with the outer sleeve 112 which is threaded into the housing 113 extending downwardly from the rear end of the receiver. The lower end of this sleeve is circular in cross section and engages in a socket in the guard 23. The sleeve 112 is provided with an inner shouldered portion 114 adjacent its lower end and the opening through this shouldered portion is squared in cross section. The screw head 115 is provided with a stem passing into the sleeve, the lower part of the stem bein squared to fit the shouldered portion of t e sleeve and the upper end of the stem being threaded to receive the sleeve 117. The spring 116 surrounds the median portion of the stem, its lower end bearing against the shoulder 114v in the sleeve 112 and its upper end against the sleeve 117. The screw head 115 is hexagonal in shape 'and the guard is correspondingly countersunk to receive a portion of the head and to thus prevent rotation.

In assembling the breech closure the sear 51 is placed in the sleeve 29 and its pin 52 is slipped laterally into place, the springA 56 having been placed about the pin 55. The bolt sleeve 20 is slipped over the forward end l of the ring pin 32 and the firing pin spring 35 is then slipped on the firing pin and compreed against the sleeve and the washer member 33'is slipped laterally into place. The locking sleeve 26 is threaded on to the rear-end of the bolt, the pusher 36 is slipped upon the rear of the assembly and the firing pin assembly is then slipped in through the rear end of the bolt 25 and screwed in place.

The receiver lock sleeve 104 is slipped into the receiver through its rear end and screwed in place. The bolt assembly is then-slipped into the receiver through the rear end, the disconnecter lug 30 passing into its longitudinal slot in the lower side of the receiver.

The recoil spring 49 is placed against the rear face of the pusher 36 and the shutter soa serted through the bottom of the receiver f and retained in place by the pivot pin 59. The springs 98 and 103 'are slipped in place in the guard, the cut out 100 placed in the guard and its pivot pin 101 inserted through it. The disconnecter 76 is placed in the guard and the magazine catch 97 is hungupon its pivot. The rear end of the trigger bar 63 is placed in the bearing 64 after having interfit with either one of two spaced inden` tations 41 in the receiver cap 41. The parts are retained in engagement by the pressure of the recoil spring. Referring to Fig. 2, the gun is ready to fire with the parts in the position shown, when the lever 45 has been swung to the right to uncover the slot 128 lto permit movement of the actuating` handle 27 and to unlock the disconnecter lug 30 and the pin 55 of the sear 51. When in the locked condition the protuberance 40 is intertted with one indentation 41 as shown in the figure and when unlocked it is fitted into another such indentation.

After unlocking the piece, pressure upon the trigger 65 moves the trigger bar 63 forward, rotating the tripper 58 about its pivot 59. Fig. 3 shows the tripper rotated and its camming surface forcing rearwardly the contact portion 57 of the sear 51, thus causing the sear to rotate on its pin 52 thereby releasing the notch 53 in the Sear from the rin pin notch 54. The spring 35 eX; pan ing between the washer 34 and bolt sleeve 29, forces the firing pin forward and fires the cartridge.

The pressure of the expanding gases in the barrel 21 is transmitted by the bolt head to the bearing surfaces of the threads connecting the locking sleeve 26 to the bolt 25,

and the locking sleeve is caused to rotate on the bolt and in the receiver sleeve 104 because the helix angle of the threads between the bolt and locking sleeve is not as great as the helix angle of the outer interrupted threads 105 and 105 between the locking sleevev26 and the fixed receiver sleeve 104.

The threads between the bolt and locking sleeve are continuous. The interrupting of the outer threads 'permits the locking sleeve, and consequently the bolt assembly, to pass rearwardly in the receiver after the lock has rotated a suiiicient part of a revolution to disengage threads 105 and 105". These threads are preferably placed upon what has been referred to as the Blish angle, an angle Such that the bolt will remain locked under4 high breech pressure but will automatically open when the pressure is lowered to a predetermined safe working limit.

The release of the locking sleeve from engagement with the receiver sleeve permits the bolt to move rearwardly in the receiver 20 against the recoil spring d 49 until the energy of recoil is absorbed or until the rear end of the bolt sleeve 29 strikes the buffer 47.

As the locking sleeve 26 is rotated in the unlocking movement the cam surfaces 26 acting on the opposed cam surfaces 36 on the pusher 36 serve to thrust the pusher rearwardly relatively to the bolt sleeve 29 and the bolt 25 and during this motion the lug 37 engages the upper end 39 of the firing pin and draws the pin rearwardly `to the position for sear notch 53 again toengage the firing pin notch 54, the notches retaining the firing pin cocked when the pusher moves forward during the closing movement. The retracted or recoil position of the parts is shown in Fig. 5, and the forward position in Fig. 2.

The disconnecter 71 is kept from rotation clockwise from normal position by shoulders 71 which bear against `the trigger bar. The disconnection spring 72 serves to return theJ disconnecter to normal osition when it is rotated in the counter c ockwise direction. Since the disconnecter cannot rotate in the clockwise direction, the disconnection lug 30 engaging the upper portion 74 of the disconnecter at the beginning of the rearward movement of the breach assembly forces the' disconnecter and the trigger bar 63 downward against the spring 69, the trigger bar being disconnected from the tripper 58 as shown in Fig. 4. The tripper 58 is then returned to its normal position yby the spring 61. During the counter recoil movement of the bolt assembly, should the disconnection' lug 30 strike the disconnecter 71 it is merely rotated against the spring 72 which returns it to place after the lug 30 passes.

elease of pressure on the trigger after disconnection permits the spring 67 to move the trigger bar rearwardly and swing the trigger to normal position. The trigger bar 63 is forced upward by the spring 69 as its forward end clears the tripper 58 and it again engages the notch 62 upon the tripper. The parts are again in the position shown in Fig. 2 and a second pull upon the the semi-automatic fire.

Moving the disconnecter operating member 75, rearwardly by means of the finger piece76 until the catch 78 coacts with the ltrigger will lire another shot and continues rear notch 80, the member` 75 engages the lower portion of the discon-necter 71 and wise direction and holdsl itdown against the spring as shown in Flg. 11. The lug 30 does not now contact with the portion 74 as it moves rearwardly and the trigger bar holds the tripper 58 tilted rearwardly. As the closing movement of the bolt mechanism is completed the contact portion 57 of the sear engages the tripperand the lower end of the Sear is swung rearwardly releasing the firing pin. This completes a 'cycle of automatic action and the piece will upon the finger piece 82 will draw down the lock sleeve.

continue to 'fire until the magazine is empty or until pressure upon the trigger is released. l

The ejector 81 on the bolt stop member 81, slides in groove 25 upon the lower side of the bolt and rises as the top of the groove inclines upward at the forward end of the bolt, the spring 83 forcing the member upward until the bolt stop release 91 contacts with the portion 92 of the receiver. As the bolt closes the ejector is pressed downward by contact with the top of the groove in the bolt. y

When the magazine is empty the lug 94 contacts with the part 95 of the bolt stop release so that as the bolt stop rises the upper arm 91 passes in the rear of the re- Ycelver portion 92 and the bolt stop passes upward sufiiciently for the forward end of the bolt to be caught by the part 87 and i f the bolt thus to be retained open. The Abolt stop release may also be manually tilted by the cut out 100 which can be turned to engage `the lower end of the bolt stopv release. The cut out is actuated by the linger piece 102 best shown in Figs. 8 and 9, and 10, and

is yieldably held in either position by squared contact with the spring 103." Except when blocked by the cut-out, a pull bolt stop and release the bolt which will be immediately closed by the power of the recoil spring.

'The magazine is held in the piece by the engagement of the catch 97 with thema'gazine `lug 96. The magazine may be released by pressing forward the lower end 99 of the catch.

The bolt lock sleeve actuating handle 27 recoils with-the bolt and has the combined rotary and reciprocating movement -of the During therlirst part of the opening movement the handle rotates onia line parallel to the helix angle of the outer threads 105 and 105', but when these threads 110 are ldisengaged. the turning movement is gradually changed to a rectilinear movement by contact between the handle and the slot 28, th`e change being a gradual curve as best shown in Figs. 1 and 6. The closing 116 movement is the reverse of this just described and the curve is so designed that the shock of changing the direction of motion is absorbed as gradually as possible This absorption is aided by/-the` lateral thrust of the interengaging cams between' the pusher and lock sleeve.

I claim- 1. A gun comprising a receiver, breec closing mechanism adapted to reciprocate in 126 the receiver, the breech closure comprising a non-rotating bolt and la rotating sleeve thereon having lugs adapted to engage with lugs in th-e receiver, the engaging angle between the sleeve lugs and the lugs in the re- 130 ceiver being inclined to the line of breech pressure at such angles as to hold the breech closing mechanism in closed position at high breech pressure and to slide relatively to each other when the pressure drops to a low value whereby the breech closure is automatically unlocked.

2. A gun comprising a receiver, breech closing mechanism adapted to reciprocate in the receiver, the breech closure comprising a non-rotatii g bolt and a rotating sleeve thereon having lugs adapted to engage with lugs in the receiver, and an actuating arm upon said sleeve, the actuating arm extending outwardly through the receiver, the engaging angle between the sleeve lugs and the lugs in the receiver being inclined to the line of breech pressure at such angles as to hold the breech closingmechanism in closed position at high pressure and to slide relatively to each other when the pressure drops to a low value whereby the breech closure is automatically unlocked.

3. A gun comprising a receiver, breech closing mechanism adapted to reciprocate in the receiver, the breechclosure comprising a non-rotating bolt and a rotating sleeve thereon having lugs adapted to engage with lugs in the receiver, helical connecting means between the bolt and sleeve, and the engaging angle 4between the sleeve lugs and the lugs in the receiver being so related to the angle of the helix that the breech pressure serves to rotate the sleeve upon the bolt.

4. A gun comprising `a receiver, breech closing mechanism adapted to reciprocate in the receiver, the breech closure comprising a non-rotating bolt and a` rotating sleeve thereon having lugs adapted to engage with lugs in the receiver, helical connecting means between the bolt and sleeve, and the engaging angle between the sleeve lugs and the lugs in the receiver having a greater angle relative to the line of breech pressure than that of the helix.

5. A gun comprising a receiver, breech closing mechanism adapted to reciprocate in the receiver, the breech closure comprising a non-rotating bolt and a vrotating sleeve thereon having lugs adapted to engage with lugs in the receiver, helical connecting means between the bolt and sleeve, and the engaging angle between the sleeve lugs and the lugs infthe receiver being so related to the angle of the helix that the breech pressure serves to rotate the sleeve upon the bolt, the engaging angle between the sleeve lugs and the lugs in the receiver being inclined to the line of breech pressure at such angles as to hold the breech closing mechanism in closed position at high breech pressure and to slide relatively to each other when the pressure drops to a low value whereby the breech closure is automatically unlocked.

6. A gun comprising a receiver, breech closing mechanism adapted to recipocate in the receiver, the breech closure comprising a non-rotating bolt and a rotating sleeve thereon having lugs adapted to engage with the lugs in the receiver, helical connecting means between the bolt and sleeve, and the -engaging angle between the sleeve lugs and the lugs in the receiver having a greater angle relative to the line of breech pressure than that of the helix, the engaging angle betweenthe sleeve lugs and the lugs in the receiver being inclined to the line of breech pressure at such angles as to holdthe breech closing mechanism in closed position at high breech pressure and to slide relatively to each other when the pressure drops to a low value whereby the breech closure is automatically unlocked. f

7 A gun comprising a receiver, breech closing mechanism adapted to reciprocate in the receiver, the breech closure comprising a non-rotating bolt and a rotating sleeve thereon having lugs adapted to engage with lugs in the receiver, and an actuating arm upon said sleeve, the actuating arm extending outwardly through the receiver, the engaging angle between the sleeve lugs and the lugs in the receiver being inclined to the line of breech pressure at such angles as to hold the breech closing mechanism in closed position at high pressure and to slide relatively to f each other when the pressure drops to a low value whereby the breech closure is automatic lly unlocked, the actuating arm moving in a slot in the receiver whereby the movement of the Sleeve is guided.

8. A gun comprising a receiver, breech closing mechanism adapted to recipocate inr the receiver, the breech closure comprising a non-rotating bolt and a rotating sleeve thereon having lugs adapted to engage with lugs in the receiver,rhelical connecting means between the bolt and sleeve, and the engaging angle between the sleeve lugs and the lugs in the receiver being so related to the angle of the helix that the breech pressure serves to rotate the sleeve upon the bolt, and an arm` extending from the sleeve and means coacting with the arm whereby the movement of the sleeve is guided while the sleeve lugs and the lugs in the receiver are disengaged.

9. A gun comprising a receiver, breech closing mechanism adapted to reciprocate in the receiver, the breech closure comprising a non-rotating bolt and a rotating sleeve thereon having lugs adapted to .engage wlth lugs in the receiver, helical connecting means between the bolt and sleeve, the engaging angle between the sleeve lugs and the lugs' in the receiver having a greater angle relative to the line of breech pressure than that of the helix, and an arm extending from the sleeve and means coacting with the arm whereby the movement of the sleeve is guided while the sleeve lugs and the lugs in the receiver are disengaged.U

j 10. In a gun, a movablebreech closure, firing means associated therewith, a trigger operatively connected to the firing means,

means adapted to contact with the breech closure during its movement to disconnect the trigger and firing means, and means adapted to selectively place the disconnecting means into or out of operation.

11. In a gun a movable breech closure, firing means associated therewith, a trigger operatively connected to the ring means, a member adapted to contact with the breech closure during its movement to disconnect the trigger and fring'means, and a member adapted for manual operation and adapted to move the disconnecter member to such position as to be out of the path of the breech closure.

12. In a gun a movable breech closure, firing means associated therewith, a trigger operatively connected to the firing means, a member adapted to contact with the breech closure during its movement to disconnect the trigger and firing means, a member adapted for manual operation and adapted to rotate the disconnector member to such position as to be out of the path of the breech closure, and spring means adapted to normally maintain the disconnecter in operative position.

13. A gun comprising a receiver, breech closing mechanism adapted to reciprocatein the receiver, a firing member and a sear carried by the breech closure, a tripping member and a trigger associated with the breech closure, the tripping member being operatively associated with the trigger by means of a trigger bar, a disconnecter member carried by the bar and having a portion adapted to extend into the reciprocatory path of the breech closure whereby it is engaged by the breech closure and the trigger bar is disconnected from the tripper.

14. A gun comprising a receiver, breech closing mechanism adapted to reciprocate in the receiver, a firing member and a sear carried by the breech closure, a tripping member and a trigger associated with the breech closure, the tripping member being operatively associated with the trigger by means of -a trigger bar, a disconnecter member carried by the bar and having a portion adapted to extend. into the reciprocatory path of the breech closure whereby it is engaged by the breech closure and the trigger bar is disconnected from the tripper, and a manually operable member adapted to move the disconnecter out of the path of the breech closure.

15. In a gun, a bolt, a bolt stop, means normally urging the bolt stop toward operative position, means adapted to retain the bolt stop in inoperative position, and manually operable means adapted to move the retaining means to permit' the bolt stop tomove to operative position.

16. In a gun, a bolt, a bolt stop, means normally urging the bolt stop toward operative position, means adapted to retain the bolt stop in inoperative position, a magazine, and a magazine follower, means upon the follower adapted to contact with the retaining means to move the retaining means to permit the bolt stop to move to operative position when the magazine is empty, and manually operable means adapted to move the retalning means to permit the bolt stop to move toloperative position.

17. In a gun, a rece1ver, a bolt,. a movable member adjacent the-bolt having a portion adapted to move into the path of the bolt, resilient means urging it toward said path, a'nd adjustable means carried by the movable member and adapted to contact with a portion of the receiver to limit themovement of the member.

18. In a gun, a receiver, a bolt, a movable.-

adapted to move into the path of the bolt,

resilient means urging it toward said path, adjustable means carried by the movable member and adapted to contact with a portion of the receiver to limit the movement of the member, and manually operable means adapted to move the adjustable means to permit greater movement of the movable member.

20. In a gun, a receiver, a bolt, a movable member adjacent the bolt having a portion adapted to move into the path of the bolt, resilient means urging it toward said path,

and adjustable means carried bythe movable member and adapted to contact with a portion of the receiver to'limit the movement of the member, the movable member being adapted to act as an ejector with the adjustable means in one position and as a bolt stop with the adjustable means in another position.

21. In a gun, a receiver, a bolt, a movable member adjacent the bolt having a portion adapted to move into the path of the bolt, resilient means urging it toward said path, and adjustable means carried by the movable member andadapted to contact with a portion of the receiver to limit the movement of the member, a magazine, a magazine follower and means upon the follower adapted to f contact with the adjustable means to vary its adjustment. Y

22. In a gun, a receiver, a bolt, a movable member adjacent the bolt having a portion adapted to move into the path cf the bolt, resilient means urging it toward said path, and adjustable means carried by the movable member and adaptedv to contact with a portion of the receiver to limit the movement of the member, a magazine, a magazine follower and means upon the follower adapted to contact with the adjustable member to move `it so as to permit the movable member to move into the path of the bolt to act as a bolt stop when the magazine is empty.

23. 'In a gun, a receiver, a breech closing mechanism movable therein, a sear carried by said mechanism, and a shutter in the receiver adapted to be moved to block the sear.

24.-. In a gun, a receiver, a breech closin mechanism movable therein, a sear carrie by said mechanism, and a shutter in the receiver adapted to be moved to block the Sear, and when so moved serving also to block the breech closing mechanism.

25. In a gun, a receiver, a breech closing mechanism movable therein, a sear carried by said mechanism, and a tubular shutter rotatable in the receiver and adapted in one position to block the sear and breech closing mechanism.

26s In a gun, a receiver having a slot therein, breech closing mechanism in thereceiver having a portion extending outwardly through the receiver slot and a shutter adapted to be moved to block the sear and the breech mechanism and to close the receiver slot.

27. In a gun, a receiver having a slot y therein, breech closing mechanism in the receiver having a portion extending outwardly through the receiver slot and a shutter adapted to be moved to close the receiver slot, the shutter -having an inwardly extending portion at its rear end adapted to receive a recoil buiiier.

28. therein, breech closing mechanism in the receiver having a portion extending outwardly through the receiver slot and a shutter adapted to be moved to close the receiver slot, the shutter having an inwardly extending portion at its rear end adapted to receive a recoil buii'er, a recoil spring, and a bul'erfhousing fitting over the buffer and having a vflange adapted to receive the thrust of the recoil spring. v

29. In a gun, a `receiver having a slot therein, breech closing mechanism in the receiver having a portion extending outwardly through the receiver slot and a shutter adapted to be moved to close the receiver slot, a rear closure for the receiver having In a gun, a receiver having a slot spring and means for4 transmitting they thrust of the spring to the shutter, a raised portion on the rear face of the shutter adapted to fit on one ot the indentations on the receiver closure, and a shutter operating lever adapted to be non-rotatably interfitted to the shutter and to extend exteriorly of the receiver.

31. A gun comprising a receiver, a breech mechanism having a non-rotating portion and a rotating locking sleeve, a pusher in said receiver adjacent the breech mechanism and a recoil spring bearing against the pusher, a portion of the pusher engaging the non-rotating portion of the breech mechanism to prevent rotation of the pusher.

32. A gun comprising a receiver, a breech mechanism having a non-rotating portion and a rotating locking sleeve, a firing member carried by the breech mechanism, a nonrotating pusher in said receiver adjacent the breech-mechanism, a recoil spring bearing againstthe pusher, a portion of the pusher engaging the ring member to move it to cocked,4 position during the opening movement of the breech mechanism.

33. A gun comprising a receiver, a breech mechanism having a non-rotating portion and a rotating locklng sleeve, a firing member carried by the breech mechanism, a non-rotween thelocki'ng sleeve and pusher whereby the pusher is moved rearwardly relative to the non-rotating portion of the breech mechanism during the opening movement of the breech mechanism,` a portion of the usher engaging the ring member to move 'itl to cocked position during the opening movement," of the breech mechanism.

34:. A gun comprising a receiver,a breech mechanism having anon-rotating portion and a rotating locking sleeve, a pusher in said receiver adjacent the breech mechanism and a recoil spring bearing against the pusher, a portion lof the pusher engaging the non-rotating portion of the breech mechanism to prevent rotation of the pusher, and interengaging cam surfaces upon the pusher and the rotating breech locking member whereby the pusher is forced rearwardly 'y against the recoil spring during the unlockfing rotation of the locking sleeve, and Where-x by the spring acts to assist the locking rotation of the sleeve.

35. A gun comprising a receiver, a breech mechanism' 'having a non-rotating portion and'a rotating lockingA sleeve,'al pusher in,

said receiver adjacent the breech mechanism and a recoil spring bearing against the pusher, a portion of the pusher engaging the non-rotating portion` of the breech mechanism to prevent rotation of the pusher, and a forwardly extending cam lug upon the pusher engaging a cam surface upon the locking sleeve, whereby the pusher is forced rearwardly against the reco1l spring during the unlocking rotation of the locking sleeve, and whereby the spring acts to assist the locking rotation of the sleeve.

36. A gun comprising a receiver, a breech mechanism having a non-rotating portion and a rotating locking sleeve, a pusher'in said receiver adjacent the breech mechanism and a recoil spring bearing against the pusher, a portion of the pusher engaging the non-rotating portion of the breech mechanism to prevent rotation of the pusher, and a forwardly extending cam lug upon the pusher engaging a cam surface upon the locking sleeve, whereby the pusher is forced rearwardly against the recoll spring during `the unlockingrotation ofthe locking sleeve,

and, whereby the spring acts to assist the locking rotation o f the sleeve, the cam surfaces being in engagement both when the breech mechanism is in locked position and when the breech mechanism is in unlocked position.

37. A gun' comprisinga receiver, a breech mechanism having a non-rotating portion and a rotating locking sleeve, a firing member carried by the breech mechanism, a nonrotating pusher in said receiver adjacent i the breech mechanism, a recoil spring bearing against the pusher, forwardly extending cam lugs upon the pusher engaging cam surfaces upon the locking sleeve, whereby the pusher is forced rearwardly against the recoll spring during the unlockin rotation f of the locking sleeve, and where y the reco1l sprlng acts to assist the locking rotation of the sleeve, a portion of the pusher engaging the firing member to move it to cockedwhen in the inoperative position serving asA an ejector.

Signed by me at Boston, Massachusetts, this 25th day of August, 1920.

\ THEODORE H. EICKHOFF. 

